Dell 2208WFP Service Manual page 16

- Button "Power" on front bezel connects to U108 (RTD2122L) #9 through CN104 #8, U108 #9 is
defined as power on/off.
- Button "+" on front bezel connects to U108 (RTD2122L) #47 through CN104 #4, U105#47 Voltage
is defined as "Plus".
- Button "-" on front bezel connects to U108 (RTD2122L) #22 through CN104 #3, U105 #22 Voltage
is defined as "Minus".
- Button "Menu" on front bezel connects to U108 (RTD2122L) #21 through CN104 #2, U105 #21
Voltage is defined as "Menu".
- Button "SELECT" on front bezel connects to U108 (RTD2122L) #14 through CN104 #1, U105 #14
Voltage is defined as "SELECT".
- LED Indicator on Front Bezel
a. When press button "power", U108 (RTD2122L) #1 be send in low Voltage, make Q107#3 sends
out high Voltage , and then to CN01#5 on keypad, LED green on.
b. When in "Suspend" mode, U108 (RTD2122L) #48 sends out a low Voltage, make Q108#3 sends
out high Voltage and then to CN01 #7 on keypad, LED Amber ON.
2.3.4 MATAR CHIP U105 (RTD2545LH)/U108(RTD2122L)
- U105 (RTD2545LH) #21~#28 output 8 bit even and #29~#38 output 8 bit odd LVDS digital data to
panel control circuit through CN103.
- U108(RTD2122L) #39 output PPWR "H" potential to make Q104 conducted, and then make Q101
conducted, +5V flow to CN103#1~#3 as Panel Vdd .
- U108(RTD2122L) #20 output CCFL_ON/OFF "L" potential to control Inverter on/off.
- U108(RTD2122L) #44 outputs Brightness "PWM" signals to control CCFL brightness.
- TCLK by Crystal 14.318MHz input to U108(RTD2122L) #15/#16.
- U108(RTD2122L)#4 is RESET signals input pin
Please refer to U105 (RTD2545LH)/ U108(RTD2122L) Pin Assignments table in page
2.3.5 Regulator Circuit
- +3.3V is generated from Regulator U101 which is supplied by+5V via R101 and through C104
filtering,
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Service Manual